One thing I had to learn is called require.js, there will be a blog post about it soonish. To get that down I wrote a little game. I call it Dodge-JS. You are a little block and have to dodge falling blocks. Some kids really liked it so I also implemented a leader board. Give it a try. I am warning you though, you may get addicted.
Once you die enter you name to have your score (time you survived) entered into the score board. Revisit or refresh the page, to play again.